LOS ANGELES: In what could prove an embarrassing case of mistaken identity for the LAPD, the female witness who identified a Russian teenager as the killer of Ennis Cosby failed to pick him out of a police line-up, instead choosing other men as the possible murderer. The news, first reported in The Los Angeles Times, suggests that police and prosecutors working on the high-profile investigation may be looking at a wall. Charles Lindner, the defense attorney for 18-year-old Mikhail Markhasev, said the woman, who is the sole witness to the January 16 shooting death, had "categorically eliminated" his client from a line-up. That casts doubt on the sketch of the killer, drawn on the basis of details supplied by the woman, which had, along with anonymous tips, led to the arrest of Markhasev. So far, Los Angeles police and the district attorney's office have refused to comment. Understandable.